Hi,
I am investigating in suspension system of vehicle and now doing the analysis for the passive suspension system on quarter car model 1 d.o.f. suppose I have only the mass, spring stiffness and damping coefficient, how can i actually evaluate the amplitude of vibration and amplitude of deflection in order to vary the damping coefficient and see how it will effect the performance of suspension system? much appreciate if anyone could help me in this
HI, The amplitude of deflection occurs at the resonance frequency while the amplitude of vibration occurs at the damped natural frequency. Maher
I suggest you to use a simple matlab code to model the phenomena and my recommendation is to use a 2 dof model instead of 1 dof.
You may find a simple description with an ode45 matlab code in for e.g. the following link http://www.cs.utexas.edu/~cline/CS323E/SpringsSolution.pdf
The code in the link should be enough to allow you to vary the damping coefficient and to get insigth on how that variation affect the performance of suspension system depending on the road excitation, e.g yroad=Yo*sin(wt). If you are familiar with Simulink you may look for similar information and codes.
Finally, remember that the amplitude of vibration is measured around the static equilibrium position. It means that the static displacement ystat=mg/k is not included in the vibration amplitude.
If you have a Simulink model, you can try with a simple bump input and check the amplitude of vibration on the sprung mass comparable to the amplitude of the input.
With the help of a simple Power Spectral Density block which acts similar to the Scope block in Simulink, you will get two natural frequencies for your sprung mass and your unsprung mass respectively.
Then, you can vary the inputs and check.
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